@charset "utf-8";
$font-size:40px;
@function bgg($px) {
  @return ($px/$font-size)*1rem;
}
html {
  font-size: $font-size;
}
.content{
    width: 100%;
    color: red;
    height: bgg(200px);
    border: 1px solid red;
    .song{
        width: 100%;
        height: bgg(130px);
        line-height: bgg(130px);
        color: yellow;
        font-size: bgg(15px);
    }
}

